Year	Percent
1990	79.02
1991	78.74
1992	78.49
1993	78.24
1994	78
1995	78.44
1996	79.02
1997	79.22
1998	78.51
1999	77.43
2000	77.93
2001	77.32
2002	77.29
2003	77.29
2004	77.46
2005	77.64
2006	77.23
2007	77.93
2008	78.06
2009	78.19
2010	77.19
2011	79.06
2012	78.66
2013	76.74
2014	75.96
2015	75.53
2016	74.73
2017	74.13
2018	74.71
2019	74.17